Capsule of microphones



ct. 13,` 1931. l l, GREINER 1,827,229

CAPSULE OF MI CROPHONES Filed NOV. 27, 1929 81%)655754M rf A TTORNE x5 Patented Oct. 13, 1931 UNITED STATES JOSEF GREINER, or VIENNA, AUSTRIA, AssrcNo-R To G. A. UNGAR AND Enrc 131mm-I MIN, `BOTH or' NEW YORK, N. Y.

CAPSULE 0F MICROPHONES Application led November 27, 1929, Serial No. 410,060, and in Austria November 29, 1928.

The microphone boxes hitherto used must be entirely removed and replaced, if they are damaged by the carbon particles having been K burnt out, since the constituents of suchmir.

crophone boxes could only be replaced in the factory by means of mechanical appliances.

Such replacement was expensive and complicated since a telephone subscriber cannot hold a stock of boxes owing to the relatively high cost of same.

This drawback is obviated by the present invention.

The improved microphone box comprises essentially two main portions and viz a metal casing and a microphone body or cartridge.

The first remains always in position of mounting, whereas the latter may be easily removed and replaced. The metal casing which forms the container of the microphone body, consists essentially of two portions, namely an upper portion clamping fast the diaphragm and a lower portion having a spring which forces the microphone body to the diaphragm of the upper portion and vholds it in position.

The second main portion, the microphone body or cartridge comprises a felt ring, which is closed by two current conducting sheets of metal or carbon, so that a cylindrical hollow space is formed for receiving the carbon particles. Such space may also be subdivided, for preventing the carbon particles from bakin together. l

uch microphone body Vis forced by a spring, to the diaphragm, and does not directly contact thesame but a small cone which is fixed either on the diaphragm or on the microphone body itself in order to avoid every damping by the different materials` which the microphone body and the diaphragm present. By obviating a rigid connection between the diaphragm and micro# phone body an excellent speaking effect is obtained. 1 Y

The microphone body may beinserted, re-

moved and replaced in a very easy and read *Il i manner, and this manipulation may be e fected by non-experts.

In the drawings: Figs. l and 2 show the microphone body. Fig. 3 isa cross section through the metal casing containing a microphone body. F ig.

4 shows the removable lower portions of the casing and Fig. 5 the upper portion of the casing. l

M is the diaphragm, G the upper portion of the casing, R a ring which secures the diaphragm M to the casing G. P represents K the microphone body which vis .pressed towards the diaphragm M by a spring F. S is a cup in which the microphone body is seated- V is the lower portion of the metal casing which is removably connected to the upperk portion G thereof by means of a bayonet joint. On said cup the spring F is seated so as to be insulated therefrom. K is a con-v tact piece which conducts the current to the spring F and to the microphone body. Figs.

4; and 5 show by way of an example a bay-v onet-joint'. The lugs r, 1' of thejoint may be passed through the openings y, y of the casing, so that by revolving one of the portions of the casing inthe direction of the arrow (Fig. 5) the lugs engage the marginal portion of the casing portion G so that j the two portions of the casing are jointed.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent is:

VMicrophone kbox comprising a casing andVlr amicrophone body, which is loosely inserted portions and a spring carried bythe second portion, which spring serves for leading current to the microphone body and presses the latter slightly to the diaphragm, said second portion being arranged so that itv may be;v

sov

readily detached from the first named portion for the purpose of removing and replacing the microphone body the interchangeable microphone body consisting of a ring made up of felt or other resilient or elastic material, which ring is covered at both sides With a current conducting plate, so that a chamber is formed for receiving the microphonic particles.

In testimony Whereoi` I affix my signature.

JOSEF GREINER. 

